Who said there's an offseason in the NFL? From Peyton Manning to Tim Tebow and the Saints bounty scandal, the NFL has continued to be at the forefront in the world of sports.

All of this news, in addition to the number of major free-agent transactions and trades that have run rampant, has made for a lot of changes in player fantasy values. Some moves, like the one that sent Jacob Tamme to the Broncos, had a domino effect that has altered the stock of several players. In an effort to get you up to date on all the news, here's our look at who's stock has risen and fallen in recent weeks. We've covered quarterbacks, running backs and wideouts, so now let's turn to tight ends.

Winners

Jason Witten, Cowboys: Witten is coming off a mediocre season by his standards, posting 79 receptions, 942 yards and five touchdowns in 2011. And while I'm not suggesting that he'll bounce back to lead all tight ends in fantasy points like he did two years ago, the loss of Laurent Robinson to the Jaguars should open up more opportunities for Witten to produce both on the field and in fantasy land. I'd take him somewhere in the middle rounds as a No. 1 fantasy tight end.

Jacob Tamme, Broncos: In 2010, Tamme took over the starting tight end spot in Indianapolis for an injured Dallas Clark - he went on to average 6.7 receptions, 63.1 yards and scored four touchdowns. Guess who was throwing him the football? That's right, his new Broncos teammate, Peyton Manning. While the team also fields Joel Dreessen and Julius Thomas at the position, Tamme is the most prominent as a pass catcher and will no doubt be a nice sleeper in fantasy drafts.

Dustin Keller, Jets: I'm not a huge fan of Keller from a fantasy perspective, simply because he starts off hot and fizzles as the season progresses. But with the Jets current depth chart, he's going to be the No. 2 option in the pass attack behind Santonio Holmes next season. That will change, of course, if the Men in Green upgrade from the likes of Chaz Schilens, Jeremy Kerley and Patrick Turner. But for now, Keller looks to be in line for a bigger role in the 2012.

Owen Daniels, Texans: Daniels was a disappointment in fantasy leagues last season, posting 54 receptions, 677 yards with three touchdowns while also finishing 16th in points at the position. Part of the reason for his lack of success was the presence of Dreessen, who was use as more of a red-zone target. But with Dreessen out of the mix, Daniels sees a slight bump in value so long as the Texans don't have add more prominent offensive weapons in the weeks to come.

Martellus Bennett, Giants: Bennett has a ton of athletic ability, but he is a bit of a "space cadet" as my pal Elliot Harrison stated in his Power rankings. Still, he's going to be in a great position to succeed in New York. Jake Ballard and Travis Beckum are both coming off knee surgeries, so Bennett could slide right into a prominent role. Remember, Eli Manning likes to throw to his tight ends (Jeremy Shockey, Kevin Boss, Ballard), so Bennett will be a deep sleeper.

Losers

Vernon Davis, 49ers: I'm on the fence with this one, because Davis was just so spectacular in the stat sheets during San Francisco's postseason run. I will say this, though - his value didn't rise as a result of the team's offensive additions. Randy Moss and Mario Manningham are now in the pass attack, joining Davis and Michael Crabtree. That's a lot of mouths to feed in an offense that doesn't throw the ball a ton. I still like Davis in the middle rounds, but owners beware.

Kellen Winslow, Buccaneers: Winslow hasn't been a true No. 1 fantasy tight end in standard leagues in recent seasons, and it's tough to envision a scenario where he'll rise back to the level in 2012. The Buccaneers are going to run the football a ton under new coach Greg Schiano, and the addition of Vincent Jackson to go along with Mike Williams and Arrelious Benn could mean a decrease in targets for the veteran out of Miami. He's now worth little more than a late rounder.

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Kyle Rudolph, Vikings: I was set to make Rudolph one of my deep sleepers for the 2012 season. That is, until the Vikings decided to bring in veteran John Carlson. While fans of Notre Dame football might like the move, Carlson's presence in the pass attack could mean fewer opportunities for Rudolph. With that said, Rudolph has more upside than his fellow Fighting Irish alum, but Carlson needs to prove that he can avoid injuries. But keep in mind, both are good pass catchers.

Tony Moeaki, Chiefs: Moeaki was a potential fantasy sleeper heading into the 2011 training camp, but he suffered a knee injury in the preseason and didn't see a single snap as a result. While reports on his rehab have been positive, Moeaki is no lock to top the depth chart after the Chiefs added veteran Kevin Boss into the offensive mix. The eventual winner could have some late-round appeal, but Moeaki is now a less attractive option in fantasy land regardless of the result.

Chris Cooley, Redskins: Remember Cooley? He was once considered an elite tight end in fantasy football. But injuries and the emergence (and subsequent franchising) of Fred Davis has made him irrelevant in fantasy land. With Davis locked into the starting role and the additions of Pierre Garcon and Josh Morgan, Cooley won't see enough opportunities to produce with the Redskins. His value would rise if he's released and signed with another team, but for now Cooley is waiver-wire fodder.